Peters



4o l l f 4a UNITED STATES PATENT OFFICE.

BENJN. BUNGE, OF NE\V YORK, N. Y.

CUT-OFF VALVE FOR STEAM-ENGINES.

Specification of Letters Patent No. 21,813, dated October 19, 1858.

To all 'whom it may concern.'

Be it known that I, BENJAMIN BUNCE, of New York, county of New York, andState of New York, have invented certain new and useful Improvements inthe Cut-Cif Valves of Steam-Engines; and I do hereby declare that thefollowing is a full, clear, and exact description of the same, referencebeing made to the annexed drawing, making a `part of this specification,in which- Figure I is a longitudinal vertical section through the steamchest. Figs. II, III and IV are of parts in detail.

Similar letters refer to similar parts throughout.

My invention is adapted to work in connection with any of the ordinaryforms of slide-valves.

The improvement lies chiefly in the mode of admitting the steam to theslide-valve, and consists in attaching to the slide itself a tube whichcommunicates from its interior with the induction passage on the face ofthe slide, and which tube is slotted on its sides to receive steam fromthe steam-chest, in which it is situated. The slotted tube is surroundedby a sleeve or cylinder, which is also slotted, and partial rotation isgiven to the sleeve so that the slots in the two may either coincide, ormay close each other, as required, by stops fixed within this chest andagainst which stops a pin projecting from the sleeve is brought tostrike as the tube and its sleeve are carried along by the movement ofthe slide-valve to which those are affixed.

I am aware that a cut-off has been made with a slotted tube andcylindrical slotted seat over it, yet this hasnot been combined with theslide-valve so as to be moved along with it, without the requirement ofan independent set of connections to give it its play.

y improvement will be readily understood by the following description ofthe construction.

The slide-valve is shown at A in Figs. I and II and has the usualopenings upon its face for admitting and exhausting steam, as (l) 21').At each side rises a hollow post A; the channels in which communicatewith the induction passages (b). Into these posts a cross tube is fittedso as to lill up the holes shown in their tops, and is so secured as tomake a steam tight joint around the external edges, the tube itselfbeing closed at both ends. This tube is seen at C, Fig. I, and is alsorepresented detached in Fig. III. The apertures are narrow slotsextending lengthwise of the tube, as at C', and may be distributedequally around the tube, as shown. The aggregate area of the wholeshould be equal to that of the induction ports. This tube forms thecut-off valve seat; the cut oft1 valve is a cylinder or sleeve dividedlengthwise into two segments and is represented at D. The bore of thisis such as to fit upon the surface of C, and through this cylinder isalso a series of slots D', of like capacity and shape with those on C.Each segment of the valve has a flange set oft as seen at (c), for thepurpose of clamping the two parts upon the tube, a space being leftbetween to form a slotopening in each side. Consequently, the two partsof the sleeve are not exactly semicylinders.

Fig. I exhibits a sectional view of the cut off valves in place withinthe steam-chest. In valve No. 2, the position shown is that wherein thesteam apertures in C and D coincide, while the valve No. l is so turnedas to exhibit the slots in C closed by the cylinder D.

The halves of D are clamped upon the tube C by screws passing throughthe set ofi flanges (e), or they may be kept together by a spring whichsha-ll be constantly acting to draw them toward each other, serving tokeep always a tight surface by closing up as fast as the wear requires.There is a pin projecting from the cylinder D by which its vibratorymotion is obtained.

The operation is as follows: The valves A, playing back and forth asusual, open the steam and exhaust ports on the great cylinder, and thecut-off is of course carried along with it. As these movements takeplace the pin strikes two stops before the slide-valve reaches the endof its stroke. By this means the cylinder D is turned partially aroundon its tubular axis C which forms its scat. These stops are on oppositesides of (i) and are represented by (O) and (O). The valves are shown athalf-stroke; No. 2 is over the exhaust port and No. l over the steamport. The pin strikes the stop (O) and the cut olf is thus turned so asto make both sets of apertures viz. D and C, coincide. The pin on valveNo.

l is shown as being struck by the stop (O), so that D has been turnedsufficiently to close the aperture C, the cut-off thereby being eected.The piston noW travels for the remainder of its stroke and the valvesare reversed. As (7)) of valve No. 2 cornes over its steam port(8),.stea1n Will pass through all the slots D and C from thesteam-chest, then through the tube C and down the hollow posts A andthrough the valve into the cylinder of the engine7 the valvefNo. l beingat that time over its eX- haust port. The pin (i) of No. 2 Will now bebrought so as to strike (O) and the cutoii' etfected by turning D7 Whilethe pin on No. l strikes the stud (O) and opens its steam passages. Thedegree of expansion Will be regulated by the position of (O),

` for the cut-oit Will be sooner or later according to its position inthe path of the slide valve. 7 hen therefore a variable cutoit' isdesired (O) is inade, adjustable by any suitable mechanical contrivanceand as shown in Fig. I. The stops (O) are always fixed.

I claim- Combining with a slide valve of ordina-ry character, a cut-offvalve, constructed substantially as Adescribed-that is to saythe slottedtube secured in a liXed position upon the slide, said tube having itsends so closed that the steam shall pass to the valve through the slots,and having also upon it y In Witness whereof I have hereunto set myhand.

BENJAMIN BUNGE. Ttnesses J. P. PIRssoN,

S. H. MAYNARD.

